1. Field of the Invention
The present invention relates to a semiconductor package module and a method of manufacturing the same, and more particularly, to a semiconductor package module having a package module without solder balls and a method of manufacturing the semiconductor package module.
2. Description of the Prior Art
Standard semiconductor package modules are area adapted to perform a specific function and include several semiconductor components or devices mounted to a single printed circuit board (PCB), also called a module board. To save on costs, modules are typically assembled using standardized parts such as memory chips and the like. After such a modularized semiconductor package module is completely assembled, the module is subject to an electrical test to check the functionality of the module. If a component mounted on a module board in such a semiconductor package module is a memory device, such as a DRAM or an SRAM, the semiconductor package module is referred to as a semiconductor memory module.
FIGS. 1A and 1B are a plan view and a cross-sectional view, respectively, of a general semiconductor package module 50.
The general semiconductor package module 50, which is a multi-layered substrate, is manufactured by mounting a plurality of semiconductor devices, for example, semiconductor packages 12, on a module board 10 in which a printed circuit pattern is formed. Connecting pads 14 for connecting a function of the semiconductor package module 50 to a mother board (not shown) are formed on one side of the module board 10.
FIG. 2 is a cross-sectional view illustrating solder balls attached to semiconductor packages of the semiconductor package module of FIG. 1. More specifically, the cross-sectional view of FIG. 2 corresponds to a portion II of FIG. 1. Referring to FIG. 2, a semiconductor package 12A has a shape of a ball grid array (BGA) and is connected to the module board 10 via solder balls 16 attached to a lower surface of the semiconductor package 12A.
A known problem with using solder balls as a connection structure between devices is the solder joint reliability (SJR) problem in which adhesion of the solder balls 16 to the module board 10 is weakened due to a difference between thermal expansion coefficients of the module board 10, which includes an insulative layer and a copper printed circuit pattern, and the semiconductor packages 12A. Further, the quality of the semiconductor device may degrade after performing a high-temperature reflow process to attach the solder balls 16 of the semiconductor packages 12A to the module board 10. Other attachment structures have been proposed to overcome this problem.
FIG. 3 illustrates an alternate electrical connection technique to the ball-grid array, showing a cross-section of the semiconductor package module of FIG. 1 when a semiconductor package has a chip on board (COB) structure such as disclosed in U.S. Pat. No. 6,312,962, patented on Nov. 6, 2001, entitled “Method for COB Mounting of Electronic Chips on a Circuit Board.” Referring to FIG. 3, a semiconductor package 12B includes a semiconductor chip 20 directly attached to the module board 10 using an adhesive element. Package 12B has a pad directly connected to a contact pad of the module board 10 via a wire 22, and is enclosed by a covering compound. However, because the semiconductor chip 20 mounted on the module board 10 is still bare, a semiconductor package module having such a COB structure is highly likely to be found out defective after being completely assembled.
To avoid this problem, a known good die, that is, a semiconductor chip whose function has been completely electrically tested, must be used. However, there are still many difficulties in developing such a known good die.
Accordingly, the need remains for alternate methods for forming packaging modules that overcome the drawbacks inherent in other methods of the semiconductor arts.